This invention relates to a magnetic head employable for a magnetic recording/reproducing device for recording and reproducing information through a magnetic recording medium.
Conventionally, a substantially rectangular parallelepiped magnetic head shown in FIG. 5 is known as a magnetic head employable for a magnetic disc device for recording and reproducing information on a magnetic recording medium such as a so-called magnetic disc formed in a disclike shape.
Referring to FIGS. 5 to 7, the magnetic head 1 is constituted of a R/W core 2, erase cores 4 exposed at both sides near a R/W gap 3 of the R/W core 2, and a slider 5 made of ceramics and integrally bonded to the cores 2 and 4. The magnetic head 1 is formed with a slide surface 6 adapted to come into contact with a magnetic disc on an upper side as viewed in the drawing. The slide surface 6 is polished in a planar shape. The magnetic head 1 is further formed with a groove 7 at a central portion thereof and a mount surface 8 to be mounted to a magnetic disc device on a lower side opposite from the slide surface 6.
In the meantime, it is known that characteristics of the magnetic head are largely varied with the length and depth (d) of the gap 3. The length of the gap 3 is determined by the thickness of a spacer such as a glass plate to be utilized in assembling each of core members 2a, 2b and 2c of the R/W core 2 as shown in FIG. 7. The depth (d) of the gap is determined by polishing the formation side of the gap 3, after integrally forming the R/W core 2 and the erase cores 4 with the slider 5. In determination of the depth of the gap, the slide surface 6 is polished as the impedance of a coil 2d wound around the R/W core 2 is measured, and when the impedance corresponding to a predetermined depth of the gap is indicated, such polishing work is stopped to obtain the predetermined depth of the gap (d). Alternatively, the depth of the gap is measure during assembly of the core members 2a, 2b, and 2c, the R/W core and the erase cores 4 are integrally formed with the slider 5, and the slide surface 6 is polished by a grinding distance (1) until the predetermined depth (d) of the gap is obtained. In any case, since the R/W core 2 and the erase cores 4 are polished from the formation side of the gap 3, there occurs a problem of dispersion in integrally forming the R/W core 2 and the erase cores 4 with the slider 5.
In other words, since the R/W core 2 and the erase cores 4 are integrally formed with the slider 5 by bonding the former to the latter with the use of low-melting glass, the slide surface 6 of the slider 5 is not always flush with the surface on the formation side of the gap 3 of the cores 2 and 4, and a slight unevenness is usually formed on the slide surface 6 before polishing. Therefore, when the slide surface 6 is polished to the predetermined depth (d) on the basis of the plane on the formation side of the gap 3 of the cores 2 and 4 (the cores 2 and 4 and the slider 5 are always formed taking into consideration the grinding distance, the height of the magnetic head 1 resultingly coincides with the height H of the slide surface 6 with respect to the mount surface. However, owing to the fact that the height H coincides with a height of the slider 5, if the height of the cores 2 and 4 is greater than that of the slider 5 after bonding, the extent of polishing of the slider 5 is reduced, thereby causing an increase in the height H. If the height of the cores 2 and 4 is smaller than that of the slider 5 after bonding, the extent of polishing of the slider 5 is increased, thereby causing a decrease in the height H. Thus, the variation generated in assembling the magnetic head 1 results in dimensional error in height which always appears in a product.
Further, as the mount surface 8 is formed on a side opposite from, the formation side of the gap 3, it is brought into contact with a mount plate 11 for the magnetic head 1 mounted to an upper side (in the drawing) of a carriage 9 at a mount portion 10 formed through the carriage 9, and fixed to the mount plate 11 by an adhesive material 17 or the like. Further, as the R/W core 2 and the coil 2d wound around the R/W core 2 are projected from the mount surface 8 side of the magnetic head 1, the mount plate 11 is required to be formed with an opening 12 for permitting the R/W core 2 to be loosely inserted therethrough. Thus, in the case that the mount surface 8 is formed on a back side with respect to the R/W gap 3 of the magnetic head 1, mounting the magnetic head 1 to the mount plate 11 is rendered complicated and presents a problem in assembling operation.
In addition, when the magnetic head 1 is mounted to the mount plate 11, variation in thickness of the mount plate 11 is added to the error in height of the magnetic head 1, and as a result, it is difficult to secure the position of the gap 3 within a predetermined tolerance, thus causing deterioration of recording/reproducing characteristics.
Furthermore, in such a conventional mounting structure as mentioned above, a shield plate 13 is wound at a peripheral portion of the magnetic head 1 after the magnetic head 1 is mounted to the mount plate 11. Although a shield effect may be enhanced by the structure, there occurs the problem that distinct parts are required and assembling steps are increased.